/* keys.c - Bluetooth key handling */

/*
 * Copyright (c) 2015-2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <atomic.h>
#include <misc/util.h>
#include <stdlib.h>
#include <string.h>
#include <zephyr.h>

#include <bluetooth.h>
#include <conn.h>
#include <hci_host.h>

#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BT_DEBUG_KEYS)
#include "log.h"

#include "gatt_internal.h"
#include "hci_core.h"
#include "keys.h"
#include "rpa.h"
#include "settings.h"
#include "smp.h"
#if defined(BFLB_BLE)
#if defined(CONFIG_BT_SETTINGS)
#include "easyflash.h"
#endif
#endif

static struct bt_keys key_pool[CONFIG_BT_MAX_PAIRED];

#define BT_KEYS_STORAGE_LEN_COMPAT (BT_KEYS_STORAGE_LEN - sizeof(uint32_t))

#if IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
static u32_t           aging_counter_val;
static struct bt_keys *last_keys_updated;
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */

struct bt_keys *bt_keys_get_addr(u8_t id, const bt_addr_le_t *addr) {
  struct bt_keys *keys;
  int             i;
  size_t          first_free_slot = ARRAY_SIZE(key_pool);

  BT_DBG("%s", bt_addr_le_str(addr));

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    keys = &key_pool[i];

    if (keys->id == id && !bt_addr_le_cmp(&keys->addr, addr)) {
      return keys;
    }

    if (first_free_slot == ARRAY_SIZE(key_pool) && (!bt_addr_le_cmp(&keys->addr, BT_ADDR_LE_ANY) || !keys->enc_size)) {
      first_free_slot = i;
    }
  }

#if IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
  if (first_free_slot == ARRAY_SIZE(key_pool)) {
    struct bt_keys *oldest = &key_pool[0];

    for (i = 1; i < ARRAY_SIZE(key_pool); i++) {
      struct bt_keys *current = &key_pool[i];

      if (current->aging_counter < oldest->aging_counter) {
        oldest = current;
      }
    }

    bt_unpair(oldest->id, &oldest->addr);
    if (!bt_addr_le_cmp(&oldest->addr, BT_ADDR_LE_ANY)) {
      first_free_slot = oldest - &key_pool[0];
    }
  }

#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
  if (first_free_slot < ARRAY_SIZE(key_pool)) {
    keys     = &key_pool[first_free_slot];
    keys->id = id;
    bt_addr_le_copy(&keys->addr, addr);
#if IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
    keys->aging_counter = ++aging_counter_val;
    last_keys_updated   = keys;
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
    BT_DBG("created %p for %s", keys, bt_addr_le_str(addr));
    return keys;
  }

  BT_DBG("unable to create keys for %s", bt_addr_le_str(addr));

  return NULL;
}

void bt_foreach_bond(u8_t id, void (*func)(const struct bt_bond_info *info, void *user_data), void *user_data) {
  int i;

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    struct bt_keys *keys = &key_pool[i];

    if (keys->keys && keys->id == id) {
      struct bt_bond_info info;

      bt_addr_le_copy(&info.addr, &keys->addr);
      func(&info, user_data);
    }
  }
}

void bt_keys_foreach(int type, void (*func)(struct bt_keys *keys, void *data), void *data) {
  int i;

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    if ((key_pool[i].keys & type)) {
      func(&key_pool[i], data);
    }
  }
}

struct bt_keys *bt_keys_find(int type, u8_t id, const bt_addr_le_t *addr) {
  int i;

  BT_DBG("type %d %s", type, bt_addr_le_str(addr));

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    if ((key_pool[i].keys & type) && key_pool[i].id == id && !bt_addr_le_cmp(&key_pool[i].addr, addr)) {
      return &key_pool[i];
    }
  }

  return NULL;
}

struct bt_keys *bt_keys_get_type(int type, u8_t id, const bt_addr_le_t *addr) {
  struct bt_keys *keys;

  BT_DBG("type %d %s", type, bt_addr_le_str(addr));

  keys = bt_keys_find(type, id, addr);
  if (keys) {
    return keys;
  }

  keys = bt_keys_get_addr(id, addr);
  if (!keys) {
    return NULL;
  }

  bt_keys_add_type(keys, type);

  return keys;
}

struct bt_keys *bt_keys_find_irk(u8_t id, const bt_addr_le_t *addr) {
  int i;

  BT_DBG("%s", bt_addr_le_str(addr));

  if (!bt_addr_le_is_rpa(addr)) {
    return NULL;
  }

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    if (!(key_pool[i].keys & BT_KEYS_IRK)) {
      continue;
    }

    if (key_pool[i].id == id && !bt_addr_cmp(&addr->a, &key_pool[i].irk.rpa)) {
      BT_DBG("cached RPA %s for %s", bt_addr_str(&key_pool[i].irk.rpa), bt_addr_le_str(&key_pool[i].addr));
      return &key_pool[i];
    }
  }

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    if (!(key_pool[i].keys & BT_KEYS_IRK)) {
      continue;
    }

    if (key_pool[i].id != id) {
      continue;
    }

    if (bt_rpa_irk_matches(key_pool[i].irk.val, &addr->a)) {
      BT_DBG("RPA %s matches %s", bt_addr_str(&key_pool[i].irk.rpa), bt_addr_le_str(&key_pool[i].addr));

      bt_addr_copy(&key_pool[i].irk.rpa, &addr->a);

      return &key_pool[i];
    }
  }

  BT_DBG("No IRK for %s", bt_addr_le_str(addr));

  return NULL;
}

struct bt_keys *bt_keys_find_addr(u8_t id, const bt_addr_le_t *addr) {
  int i;

  BT_DBG("%s", bt_addr_le_str(addr));

  for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
    if (key_pool[i].id == id && !bt_addr_le_cmp(&key_pool[i].addr, addr)) {
      return &key_pool[i];
    }
  }

  return NULL;
}

#if defined(CONFIG_BLE_AT_CMD)
bt_addr_le_t *bt_get_keys_address(u8_t id) {
  bt_addr_le_t addr;

  memset(&addr, 0, sizeof(bt_addr_le_t));
  if (id < ARRAY_SIZE(key_pool)) {
    if (bt_addr_le_cmp(&key_pool[id].addr, &addr)) {
      return &key_pool[id].addr;
    }
  }

  return NULL;
}
#endif

void bt_keys_add_type(struct bt_keys *keys, int type) { keys->keys |= type; }

void bt_keys_clear(struct bt_keys *keys) {
#if defined(BFLB_BLE)
  if (keys->keys & BT_KEYS_IRK) {
    bt_id_del(keys);
  }

  memset(keys, 0, sizeof(*keys));

#if defined(CONFIG_BT_SETTINGS)
  ef_del_env(NV_KEY_POOL);
#endif
#else
  BT_DBG("%s (keys 0x%04x)", bt_addr_le_str(&keys->addr), keys->keys);

  if (keys->keys & BT_KEYS_IRK) {
    bt_id_del(keys);
  }

  if (IS_ENABLED(CONFIG_BT_SETTINGS)) {
    char key[BT_SETTINGS_KEY_MAX];

    /* Delete stored keys from flash */
    if (keys->id) {
      char id[4];

      u8_to_dec(id, sizeof(id), keys->id);
      bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr, id);
    } else {
      bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr, NULL);
    }

    BT_DBG("Deleting key %s", log_strdup(key));
    settings_delete(key);
  }

  (void)memset(keys, 0, sizeof(*keys));
#endif
}

static void keys_clear_id(struct bt_keys *keys, void *data) {
  u8_t *id = data;

  if (*id == keys->id) {
    if (IS_ENABLED(CONFIG_BT_SETTINGS)) {
      bt_gatt_clear(*id, &keys->addr);
    }

    bt_keys_clear(keys);
  }
}

void bt_keys_clear_all(u8_t id) { bt_keys_foreach(BT_KEYS_ALL, keys_clear_id, &id); }

#if defined(CONFIG_BT_SETTINGS)
int bt_keys_store(struct bt_keys *keys) {
#if defined(BFLB_BLE)
  int err;
  err = bt_settings_set_bin(NV_KEY_POOL, (const u8_t *)&key_pool[0], sizeof(key_pool));
  return err;
#else
  char  val[BT_SETTINGS_SIZE(BT_KEYS_STORAGE_LEN)];
  char  key[BT_SETTINGS_KEY_MAX];
  char *str;
  int   err;

  str = settings_str_from_bytes(keys->storage_start, BT_KEYS_STORAGE_LEN, val, sizeof(val));
  if (!str) {
    BT_ERR("Unable to encode bt_keys as value");
    return -EINVAL;
  }

  if (keys->id) {
    char id[4];

    u8_to_dec(id, sizeof(id), keys->id);
    bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr, id);
  } else {
    bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr, NULL);
  }

  err = settings_save_one(key, keys->storage_start, BT_KEYS_STORAGE_LEN);
  if (err) {
    BT_ERR("Failed to save keys (err %d)", err);
    return err;
  }

  BT_DBG("Stored keys for %s (%s)", bt_addr_le_str(&keys->addr), log_strdup(key));

  return 0;
#endif // BFLB_BLE
}

#if !defined(BFLB_BLE)
static int keys_set(const char *name, size_t len_rd, settings_read_cb read_cb, void *cb_arg) {
  struct bt_keys *keys;
  bt_addr_le_t    addr;
  u8_t            id;
  size_t          len;
  int             err;
  char            val[BT_KEYS_STORAGE_LEN];
  const char     *next;

  if (!name) {
    BT_ERR("Insufficient number of arguments");
    return -EINVAL;
  }

  len = read_cb(cb_arg, val, sizeof(val));
  if (len < 0) {
    BT_ERR("Failed to read value (err %zu)", len);
    return -EINVAL;
  }

  BT_DBG("name %s val %s", log_strdup(name), (len) ? bt_hex(val, sizeof(val)) : "(null)");

  err = bt_settings_decode_key(name, &addr);
  if (err) {
    BT_ERR("Unable to decode address %s", name);
    return -EINVAL;
  }

  settings_name_next(name, &next);

  if (!next) {
    id = BT_ID_DEFAULT;
  } else {
    id = strtol(next, NULL, 10);
  }

  if (!len) {
    keys = bt_keys_find(BT_KEYS_ALL, id, &addr);
    if (keys) {
      (void)memset(keys, 0, sizeof(*keys));
      BT_DBG("Cleared keys for %s", bt_addr_le_str(&addr));
    } else {
      BT_WARN("Unable to find deleted keys for %s", bt_addr_le_str(&addr));
    }

    return 0;
  }

  keys = bt_keys_get_addr(id, &addr);
  if (!keys) {
    BT_ERR("Failed to allocate keys for %s", bt_addr_le_str(&addr));
    return -ENOMEM;
  }
  if (len != BT_KEYS_STORAGE_LEN) {
    do {
      /* Load shorter structure for compatibility with old
       * records format with no counter.
       */
      if (IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST) && len == BT_KEYS_STORAGE_LEN_COMPAT) {
        BT_WARN("Keys for %s have no aging counter", bt_addr_le_str(&addr));
        memcpy(keys->storage_start, val, len);
        continue;
      }

      BT_ERR("Invalid key length %zu != %zu", len, BT_KEYS_STORAGE_LEN);
      bt_keys_clear(keys);

      return -EINVAL;
    } while (0);
  } else {
    memcpy(keys->storage_start, val, len);
  }

  BT_DBG("Successfully restored keys for %s", bt_addr_le_str(&addr));
#if IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
  if (aging_counter_val < keys->aging_counter) {
    aging_counter_val = keys->aging_counter;
  }
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
  return 0;
}
#endif //!(BFLB_BLE)

static void id_add(struct bt_keys *keys, void *user_data) { bt_id_add(keys); }

#if defined(BFLB_BLE)
int keys_commit(void)
#else
static int keys_commit(void)
#endif
{
  BT_DBG("");

  /* We do this in commit() rather than add() since add() may get
   * called multiple times for the same address, especially if
   * the keys were already removed.
   */
  bt_keys_foreach(BT_KEYS_IRK, id_add, NULL);

  return 0;
}

// SETTINGS_STATIC_HANDLER_DEFINE(bt_keys, "bt/keys", NULL, keys_set, keys_commit,
//			       NULL);

#if defined(BFLB_BLE)
int bt_keys_load(void) { return bt_settings_get_bin(NV_KEY_POOL, (u8_t *)&key_pool[0], sizeof(key_pool), NULL); }
#endif

#endif /* CONFIG_BT_SETTINGS */

#if IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
void bt_keys_update_usage(u8_t id, const bt_addr_le_t *addr) {
  struct bt_keys *keys = bt_keys_find_addr(id, addr);

  if (!keys) {
    return;
  }

  if (last_keys_updated == keys) {
    return;
  }

  keys->aging_counter = ++aging_counter_val;
  last_keys_updated   = keys;

  BT_DBG("Aging counter for %s is set to %u", bt_addr_le_str(addr), keys->aging_counter);

  if (IS_ENABLED(CONFIG_BT_KEYS_SAVE_AGING_COUNTER_ON_PAIRING)) {
    bt_keys_store(keys);
  }
}

#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
